The histone-deacetylase inhibitor MS-275 and the CDK-inhibitor CYC-202 promote anti-tumor effects in hepatoma cell lines.
Effective therapies for advanced stages of hepatocellular carcinoma (HCC) have yet to be developed. We investigated how far a combination of the HDAC inhibitor MS-275 and the CDK inhibitor CYC-202 synergizes to inhibit proliferation and promotes apoptosis of hepatoma cells in vitro. Human hepatoma cell lines Hep3B and HepG2 as well as primary human foreskin fibroblasts as non-malignant controls were cultured under standardized conditions and incubated with increasing concentrations of CYC-202 and MS-275 as single agents and in combination. After 24 to 72 h, apoptosis was analyzed by flow cytometry (propidium iodide, JC-1) and by immunocytochemistry for cytokeratin 18 fragmentation. DNA synthesis was assessed using bromodeoxyuridine incorporation. Protein was separated for Western blotting against p21, bax and bcl-2 and fluorimetric activity assays against caspase 3 and 8. The results showed that the combination of CYC-202 and MS-275 leads to better pro-apoptotic effects than the employment of single substances. Apoptosis was induced via the mitochondrial pathway as evidenced by a shift in the bax/bcl-2 ratio and breakdown of mitochondrial transmembrane potentials. Caspase assays revealed a strong induction of caspase 3 but not of the extrinsic initiator caspase 8. In conclusion, combination therapy with the biomodulators MS-275 and CYC-202 is a promising treatment option for HCC.
Gahr
Susanne
S
Department of Medicine 1, University Hospital Erlangen, Erlangen, Germany.
Peter
Gisela
G
Wissniowski
Thadäus Till
TT
Hahn
Eckhart G
EG
Herold
Christoph
C
Ocker
Matthias
M
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides / Q000494:pharmacology*; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D053148:Caspase 3 / Q000187:drug effects; D053181:Caspase 8 / Q000187:drug effects; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000378:metabolism*; D011687:Purines / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D000077546:Roscovitine
D000970:Antineoplastic Agents; D001549:Benzamides; D004791:Enzyme Inhibitors; D011687:Purines; D011725:Pyridines; D000077546:Roscovitine; C118739:entinostat; D053148:Caspase 3; D053181:Caspase 8